Search results for "X-Ray"
showing 10 items of 4234 documents
Design and optimization of the wide-field spectrometer for EDGE mission
2007
The LOFT mission concept: a status update
2016
The Large Observatory For x-ray Timing (LOFT) is a mission concept which was proposed to ESA as M3 and M4 candidate in the framework of the Cosmic Vision 2015-2025 program. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument and the uniquely large field of view of its wide field monitor, LOFT will be able to study the behaviour of matter in extreme conditions such as the strong gravitational field in the innermost regions close to black holes and neutron stars and the supra-nuclear densities in the interiors of neutron stars. The science payload is based on a Large Area Detector (LAD, >8m2 effective area, 2-30 keV, 240 eV spectral resolut…
INTEGRAL long-term monitoring of the Supergiant Fast X-ray Transient XTE J1739-302
2008
In the past few years, a new class of High Mass X-Ray Binaries (HMXRB) has been claimed to exist, the Supergiant Fast X-ray Transients (SFXT). These are X-ray binary systems with a compact companion orbiting a supergiant star which show very short and bright outbursts in a series of activity periods overimposed on longer quiescent periods. Only very recently the first attempts to model the behaviour of these sources have been published, some of them within the framework of accretion from clumpy stellar winds.Our goal is to analyze the properties of XTE J1739-302/IGR J17391-3021 within the context of the clumpy structure of the supergiant wind. We have used INTEGRAL and RXTE/PCA observations…
IBIS: The Imager on-board INTEGRAL
2003
The IBIS telescope is the high angular resolution gamma-ray imager on-board the INTEGRAL Observatory, successfully launched from Baikonur (Kazakhstan) the 17th of October 2002. This medium size ESA project, planned for a 2 year mission with possible extension to 5, is devoted to the observation of the gamma-ray sky in the energy range from 3 keV to 10 MeV (Winkler 2001). The IBIS imaging system is based on two independent solid state detector arrays optimised for low ( 15-1000 keV) and high ( 0.175-10.0 MeV) energies surrounded by an active VETO System. This high efficiency shield is essential to minimise the background induced by high energy particles in the highly excentric out of van All…
The Be/X-ray transient 4U0115+63/V635 Cassiopeiae : II. Outburst mechanisms
2001
We present multi-wavelength long-term monitoring observations of V635 Cas, the optical counterpart to the transient X-ray pulsar 4U0115+63. The evolution of emission lines and photometric magnitudes indicates that the Be star undergoes relatively fast ( ~3 - 5yr) quasi-cyclic activity, losing and reforming its circumstellar disc. We show that the general optical, infrared and X-ray behaviour can be explained by the dynamical evolution of the viscous circumstellar disc around the Be star. After each disc-loss episode, the disc starts reforming and grows until it reaches the radius at which the resonant interaction of the neutron star truncates it. At some point, the disc becomes unstable to …
First observations of the X-ray transient EXO 2030+375 with IBIS/ISGRI
2003
We present a first INTEGRAL observation of the 42s transient X-ray pulsar EXO 2030+375 with IBIS/ISGRI. The source was detected during Cyg X-1 observations in December 2002. We analyzed observations during the outburst period from 9 to 21 December 2002 with a total exposure time of ~770 kiloseconds. EXO 2030+375 was almost always detected during single ~30 minute exposures in the 18-45 energy bands. The source light curve shows the characteristic outburst shape observed in this source.
Radiation hydrodynamic and magnetohydrodynamic models of plasma flows accreting onto Classical T Tauri Stars
2019
Contesto scientifico Le stelle T Tauri classiche (CTTSs) sono oggetti stellari giovani poco massivi che accrescono massa dal loro disco circumstellare. Il disco si estende internamente fino al raggio di tron- camento, ovvero dove il campo magnetico e` abbastanza intenso da sollevare il materiale dal piano del disco e da incanalarlo formando delle colonne di accrescimento (Koenigl 1991). Il materiale incanalato precipita sulla stella e impatta sulla superficie stellare. Gli impatti gener- ano shocks caldi. Le CTTSs sono anche caratterizzate da un alto livello di attivita` coronale, come rivelato dalle osservazioni in banda X (e.g. Favata et al. 2005). Questa attivita` coronale e` prodotta pr…
Single-Event Effects in the Peripheral Circuitry of a Commercial Ferroelectric Random-Access Memory
2018
This paper identifies the failure modes of a commercial 130-nm ferroelectric random access memory. The devices were irradiated with heavy-ion and pulsed focused X-ray beams. Various failure modes are observed, which generate characteristic error patterns, affecting isolated bits, words, groups of pages, and sometimes entire regions of the memory array. The underlying mechanisms are discussed. peerReviewed
A Novel Na(I) Coordination Complex with s-Triazine Pincer Ligand: Synthesis, X-ray Structure, Hirshfeld Analysis, and Antimicrobial Activity
2023
The pincer ligand 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine (bpmt) was used to synthesize the novel [Na(bpmt)2][AuCl4] complex through the self-assembly method. In this complex, the Na(I) ion is hexa-coordinated with two tridentate N-pincer ligands (bpmt). The two bpmt ligand units are meridionally coordinated to Na(I) via one short Na-N(s-triazine) and two slightly longer Na-N(pyrazole) bonds, resulting in a distorted octahedral geometry around the Na(I) ion. In the coordinated bpmt ligand, the s-triazine core is not found to be coplanar with the two pyrazole moieties. Additionally, the two bpmt units are strongly twisted from one another by 64.94°. Based on Hirshf…
Calibration of the SphinX experiment at the XACT facility in Palermo
2008
Three of the four detectors of the SphinX experiment to be flown on the Russian mission Coronas-Photon have been measured at the XACT Facility of the Palermo Observatory at several wavelengths in the soft X-ray band. We describe the instrumental set-up and report some measurements. The analysis work to obtain the final calibration is still in progress.